Gold finger article composed of compressed and sintered fine gold powder and a refractory oxide

ABSTRACT

A GOLD FINGER RING COMPOSED OF COMPRESSED AND SINTERED FINE GOLD POWDER HAVING UNIFORMLY DISPERSED THERETHROUGH FROM 0.03% TO 0.2% OF REFRACTORY OXIDE PARTICLES HAVING A SIZE BETWEEN 0.5 AND 5 MICRONS.

Sept. 21, 1971 GOLD FINGER ARTICLE COMP N'I'ERED S. HILL OSED 0FCOMPRESSED AND SI FINE GOLD POWDER AND A REFRACTORY OXIDE Filed June 26,1969 INVIL'NTOR.

JAMES S. H/LL United States Patent 7 ABSTRACT OF THE DISCLOSURE A goldfinger ring composed of compressed and sintered fine gold powder havinguniformly dispersed therethrough from 0.03% to 0.2% of refractory oxideparticles having a size between 0.5 and microns.

BACKGROUND OF THE INVENTION Gold finger rings are usually composed ofcast gold alloys, e.g., 14 carat gold, which contain metal alloyingcomponents such as copper, silver and zinc. It is known that because ofthe presence of these metal alloying components the skin of the humanfinger in contact with the rings is sometimes subject to a reactionwhich may cause some peeling of the skin or a greenish discoloration ofthe skin.

This would not occur if the ring was composed of 24 carat gold, i.e.pure gold, but the 24 carat gold is too soft and the ring would notretain its shape and therefore, necessitates the addition of alloyingmetal components to harden the ring.

It is herein contemplated to provide a gold finger ring of substatnially24 carat gold (fine gold) which will overcome the above-mentioneddisadvantages.

SUMMARY OF THE INVENTION In accordance with the invention, there isprovided a gold finger ring composed essentially of fine gold powder (24carat) in compressed and sintered condition having uniformly dispersedtherethrough from 0.03% to 0.2% of refractory oxide particles having asize between 0.5 and 5 microns. The oxides within this size range arepreferably obtained by the decomposition of a soluble salt of the metalforming the refractory oxide and effectively hardening the fine gold,when uniformly dispersed therethrough, to a hardness at least that of 18carat gold while providing for a ductility sufficient to make the ringsizable from about to 1 size larger than the originally formed ring.

DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an elevational side viewof the finger ring according to the invention,

FIG. 2 illustrates a cross-sectional view along lines 22 of FIG. 1, and

FIG. 3 illustrates a modification of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2 ofthe drawings, the finger ring 1 is composed of compressed and sinteredfine gold powder having uniformly dispersed therethrough from 0.03% to0.2%, preferably from 0.1% to 0.15%, of refractory metal oxide particles2 having a particle size between 0.5 and 5 microns. The refractory metaloxides are, for example, A1 0 ZrO ThO Y O SiO or MgO The following is anexample method of manufacture of the ring:

3,606,766 Patented Sept. 21, 1971 "ice EXAMPLE A 2" by 2" mold assemblywas lubricated with a solution of stearic acid in trichloroethylene andcharged with 6.0 troy ounces of fine gold powder. The gold powder waspressed in the mold under a load of 12 tons gauge pressure to yield a0.291" thick bar. The gold bar was weighed and placed in a vacuumchamber where the air in the voids in the compressed bar was evacuated.The chamber was subsequently flooded with a 40% solution of Al(NO whilethe chamber was under vacuum condition. The bar was removed, oven driedfor 16 hours at 250 C., and cooled in a dessicator. The cooled bar wasweighed and found to contain 0.10% A1 0 Next, the bar was sintered inair for 2 hours at 900 C., coined at 20 tons gauge pressure and postsintered in air for 2 hours at 900 C. The gold workpiece was rolled to a0.123" thick sheet with annealing between each rolling operation for /2hour at 750 C.-800 C. Gold rings which retain their shape and haveexcellent wear characteristics were punched from the gold sheet. Theouter surface of the rings were provided with a rounded contour bymachining.

In accordance with the above example, three gold bars were eachimpregnated with a solution containing 20%, 25% and 30% zirconiumnitrate, respectively, and provided zirconia contents of 0.10%, 0.15%and 0.27%, respectively. The thre gold bars were compressed, sinteredand rolled into workpieces similarly as in Example 1 and likewisesimilarly formed into gold rings.

It was also found that another gold bar, similarly to Example 1, wasimpregnated with a 10% solution of thorium nitrate and yielded about0.2% of ThO Wear tests were conducted on a gold sheet sample materialfrom which the rings of the invention were fabricated which clearly showthat the dispersion strengthened gold has better wear characteristicsthan either fine gold or 18K yellow gold. These wear tests wereconducted on a Taber Abraser, Model 174, under gram load with green testwheels which were dressed before each test. The sheet sample size was 1"X 2" x 20 mil thickness. The observed weight loss given in the tablebelow represents the average of three tests.

TABLE I.WEAR CHARACTERISTICS OF GOLD SAMPLES Weight loss in grams Fromthese tests it can be seen that strengthened gold with as little as.075% ThO for example, gives a composite material with better wearcharacteristics than fine gold alone; and, if fine gold is strengthenedwith up to 0.2% ThO the year characteristics even surpass 18K gold.

Regarding FIG. 3, the ring, after forming and machining, can be providedwith a flash coating 3 of gold for the purpose of being capable of ahigher polish.

While the above description relates specifically to gold finger rings,other articles of jewelry which are worn in contact with the human skinare also contemplates, such as earrings, neck chains and pendants.

I claim:

1. A gold finger ring consisting of compressed and sintered 24 caratfine gold powder having uniformly dispersed therethrough from 0.03% to0.2% by weight of refractory oxide particles having a particle sizebetween 0.5 and 5 microns.

2. A gold finger ring according to claim 1, wherein the fine fold powderhas uniformly dispersed therethrough from 0.1% to 0.15 by weight of therefractory oxide.

3. A gold finger ring according to claim 1, wherein the refractory oxideis A1 0 ZrO ThO Y O SiO or MgO.

4. A gold finger ring consisting of compressed and sintered 24 caratfine gold powder having uniformly dispersed therethrough from 0.03% to0.2% by weight of refractory oxide particles having a particle sizebetween 0.5 and 5 microns, said ring being coated with a gold flashcoating.

5. An article of jewelry comprising a metal body for contact with thehuman skin, said metal body consisting of compressed and sintered 24carat fine gold powder having uniformly dispersed therethrough from0.03% to 0.2% by weight of refractory oxide particles having a particlesize between 0.5 and 5 microns.

References Cited UNITED STATES PATENTS 3,139,682 7/1964 Grant 29182.53,150,443 9/1964 Alexander ct a1 29182.5 3,218,135 11/1965 Alexander eta1. 29-182.5

10 F. BARRY SHAY, Primary Examiner US. Cl. X.R.

